Colorectal laterally spreading tumours : subtype evaluation by EUS and BLI and outcome of ESD.

Background and study aims: Colorectal laterally spreading tumour (LST) is a specific type of colonic space-occupying lesion unlike other common polypoid lesions. Here, we explored the diagnostic values of endoscopic ultrasonography (EUS) and blue laser image (BLI) in LST subtypes, their relationship with histopathological characteristics and the therapeutic effect of endoscopic submucosal dissection(ESD) for LST.

Patients and methods: A prospective study of 138 patients with LST was conducted. All LSTs were explored for invasion depth and superficial microstructure through EUS and BLI before ESD. Histopathological characteristics of LSTs were demonstrated through pre-operative biopsy and post-operative specimen detection. Finally, the correlations among varied morphologies, manifestations of EUS and BLI, and histopathological characteristics of LSTs were analysed comprehensively. All patients underwent follow-up after ESD.

Results: Nodular-mixed and pseudodepressed subtypes were more likely to invade the submucosa, and BLI revealed a greater proportion of types B and C than the homogeneous or flat-elevated subtypes. These endoscopic features were consistent with and proved by histopathological results. Pathological severity of LST on post-ESD specimen detection was greater than that on pre-ESD biopsy analysis. En bloc R0 resection was achieved in 128 cases, and only two patients suffered recurrence during follow-up.

Conclusions: Pre-operative evaluation through EUS and BLI examination provided clues of possible pathological features and helped guide the treatment of LST. ESD is a safe and effective therapy for colorectal LST.